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Measuring the Amount of Surface Water and Groundwater

 

The Water Resources Authority of the Litani River Authority ensure the following:

  • Measuring the amount of surface water in all Lebanese rivers and springs.
  • Measuring the level of groundwater in Bekaa and the South

 

Surface water-springs
Groundwater-wells

 

Measuring the Amount of Surface Water:

Surface water in rivers and springs is measured annually from September to August (rain year) as follows:

  1. Measurement locations are determined on the river from its origin till its mouth, passing by its course.
    1. A water monitoring station is set up to record the flow of the river all day, by adopting a weekly measurement process to record the amount of water, depending on hydrological demand
  2. The Authority uses two methods to measure the amount of surface water:
    1. The reel:
      1. It is an electronic measurement device that determines the height and speed of water to calculate the quantity.
    2. Measuring by estimation
      1. The dimensions of the specified area are estimated, and the speed of the water is measured to calculate the quantity of water.
    3. The Authority also received recently modern equipment such as the « River Surveyor »
      Reel Measurement
      Reel Measurement
      River Surveyor Measurement
      River Surveyor Measurement
  3. Water monitoring stations rely on limnigraphs which are placed in cement rooms beside the river or in an iron box placed into the river by means of poles. There are different types of this device:
  4. Cement Station
    Iron Station
    1. (OTT, SEBA (Germany), SIAP (Italy)
      1. To issue the results of final measurements, the Authority uses two methods:
    2. Computers: through HYDATA and HYDRAS software used in hydraulic analysis.
    3. Hydrograph: this is used in locations where there are no monitoring devices available, and it provides monthly approximate measuring of the water quantity.
  5. After that, water analysis results are archived, graphs are drawn, tables are prepared and final results are saved. The Authority is currently working on activating the GIS technology to help pinpoint water locations on maps.

Measuring Groundwater:

The purpose of measuring the quantity of water underground is to determine the level of water in wells. Underground water is measured as follows:

  1. First, a number of wells is chosen reflecting the presence of groundwater in a certain basin. The wells are studied in a period of time determined according to geologic and hydrologic factors, to study the levels and amounts of water in the basin.
  2. Groundwater levels in wells are measured by a depthmeter, after halting the pumping of water from the well for a certain period of time, depending on the depth of the well and the nature of the aquifer. Then, its altitude relatively to sea level is recorded (mASL).
  3. The Authority is currently determining and moving the location of 29 underground wells in the South. The depth of water in these wells is monitored regularly according to a weekly schedule, to draw the wells, deduce their curves and the consumption rate of water, in order to lay a model of the flow of underground water and study its movement.
  4. As part of the LRBMS project funded by USAID, the Authority dug 15 wells dedicated to measuring the levels of groundwater in the upper Litani basin.

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